Relationships among Streptomyces spp. Causing Potato Scab

Abstract

The levels of DNA-DNA hybridization among members of the three major groups of Streptomyces spp. that cause potato scab did not exceed 20% for any pair. The majority of the Streptomyces scabies strains which we examined exhibited greater than 70% relatedness to the type strain, although values as low as 21% were obtained. The levels of homology between S . scabies and nonpathogenic type strains belonging to the Diastatochromogenes group ranged from 10 to 42 9% , while the reciprocal values obtained with labeled DNAs from Streptomyces bottropensis ATCC 25435T (T = type strain) and Streptomyces eurythermus ATCC 14975T ranged from 37 to 74% and from 2 to 24%, respectively. In contrast to S . scabies, the levels of relatedness between Streptomyces acidiscabies isolates and their type strain were high (83 to 111%). The levels of DNA relatedness within the Streptomyces aZbidoJlavus group were uniformly low. These results are consistent with phenotypic data which indicate that pathogens in the three groups are not related. The genetic diversity of strains referred to as S . scabies exceeds the genetic diversity found at the species level, and some of these strains appear to be related to phenotypically similar nonpathogens.Scab diseases of potatoes (Solanum tuberosum) and certain other root crops are caused by streptomycetes, including the major species Streptomyces scabies, which was first described by Thaxter in 1891 (11, 22), the acid-tolerant species Streptomyces acidiscabies (12), and other strains whose characteristics are consistent with those of the Streptomyces albidojlavus group of Williams et al. (11, 24). S. scabies is most closely related to the Diastatochromogenes group of Elesawy and Szabo (2), while the S. albidoflavus strains have been associated with Streptomyces griseus and Streptomyces tendae (7). The results of studies of 42 phenotypic traits (11, 12) have suggested that these three pathogen groups are not closely related and that the levels of strain diversity are lowest for S . acidiscabies and greatest for the S . albidoflavus group. The purposes of this study were to confirm these relationships, to determine the genomic relationship of S . scabies to the Diastatochromogenes group, and to interpret the significance of common pathogenicity mechanisms among potato scab pathogens. MATERIALS AND METHODSStrains. The isolates which we used are listed in Table 1 DNA extraction. Total DNAs were isolated from Streptomyces strains by using the method of Hintermann et al. (6), with some modifications. Mycelia grown in Trypticase soy broth shake cultures were homogenized, centrifuged, rinsed, and suspended in 5 ml of cold TS buffer (50 mM Tris, 0.75 M sucrose; pH 8.0). Lysozyme hydrochloride and EDTA were added to concentrations of 5 mg/ml and 0.1 M, respectively.After incubation at 37°C for 1 h, 1 mg pronase E per ml was added, and incubation was continued for 15 min. Sodium dodecyl sulfate was added to a concentration of 1%, and the suspensions were incubated at 37°C until full lysis was achieved (30 to 6...

DNA relatedness among strains of Streptomyces pathogenic to potato in France: description of three new species, S. europaeiscabiei sp. nov. and S. stelliscabiei sp. nov. associated with common scab, and S. reticuliscabiei sp. nov. associated with netted scab.

“…We obtained GjC content of 70n3 mol % for the reference strains, S. scabies CFBP 4517 T and S. acidiscabies CFBP 4539 T , which was consistent with the values of 70n5 mol % (CFBP 4517 T ) and 71n1 mol % (CFBP 4539 T ) determined previously (Healy & Lambert, 1991).…”

“…S. scabies strains form a relatively homogeneous group on the basis of the limited number of phenotypic features studied (Lambert & Loria, 1989a ;Faucher et al, 1992). However, molecular studies involving techniques such as DNA-DNA hybridization have shown a great diversity within the strains identified as S. scabies (Healy & Lambert, 1991 ;Paradis et al, 1994). Other species, including Streptomyces acidiscabies (Bonde & McIntyre, 1968 ;Lambert & Loria, 1989b), Streptomyces caviscabies (Faucher et al, 1995 ;Goyer et al, 1996), and other as yet unnamed species of Streptomyces (Doering-Saad et al, 1992), also cause common scab.…”

Reassessment of the status of Streptomyces setonii and reclassification of Streptomyces fimicarius as a later synonym of Streptomyces setonii and Streptomyces albovinaceus as a later synonym of Streptomyces globisporus

“…However, our observation is in line with a low level of DNA-DNA relatedness between the two type strains (43 %) observed in an earlier study (Healy & Lambert, 1991). Furthermore, a comparison of earlier phenotypic descriptions of the two species, such as melanin production by S. griseus in tyrosine agar in contrast to S. setonii and differences in carbon source utilization patterns between the two (Shirling & Gottlieb, 1968, clearly supports our observation.…”

A Patchwork of Streptomyces Species Isolated from Potato Common Scab Lesions in North America

“…With the advent of molecular genetic characterization of CS-causing species, it became apparent that Streptomyces scabies was a complex of species (BouchekMechiche et al 2000;Bukhalid et al 2002;Doering-Saad et al 1992;Healy and Lambert 1991;Takeuchi et al 1996). Morphological, physiological and molecular evidence currently supports the designation of about ten CS-causing species known from one or more geographic locations around the world.…”